Just trying to reconcile the speedo buffer diagram, Phonedawgs instructions for his buffer, Darth's 7730 pinning instructions, and an already completed harness. Here's my schematic with questions in [PARENTHESIS & CAPS]:

7730 ECM
BA6 - Pink/Black - To speedo buffer (pink wire)
BB9 - Purple - VSS connector at trans. [DARTH'S INSTRUCTIONS SAY THIS GOES TO C203 PIN R? R IS DISCONNECTED ACCORDING TO PHONEDAWGS AND THE DIAGRAM.]
BB10 - Yellow - VSS connector at trans. [DARTH'S INSTRUCTIONS SAY THIS GOES TO C203 PIN G?]
BB11 - Green/White - To buffer (green wire) [EVEN THOUGH THIS SAYS 4K OUT FOR DIGITAL CRUISE IN DARTH'S INSTRUCTIONS?]

Buffer
Green - To ECM BB11 [BUFFER DIAGRAM HAS THIS AS A 4K OUR FOR DIGITAL CRUISE (I'M NOT RUNNING CRUISE)]
Yellow - To C203 pin G [AGAIN, DARTH'S INSTRUCTIONS HAS THE ECM CONNECTING HERE?]
Pink (cut end) - To C203 pin F
Pink (w/ connector) - To ECM BA6 [ECM IS JUMPING POWER OFF THE BUFFER. OKAY THAT ITS A SMALLER GAUGE WIRE?]


Spoke to the builder of the harness, and he said I'd need to add a buffer. The existing swap harness has the VSS from the trans. connected to the C203. From the ECM, BB9, BB10, and BB11 we're all loose wires. There was a pin coming off the harness labeled "VSS 4k". Can't seem to tell where that goes with my multimeter.

I'm thinking maybe he PO had the buffer wired in the car, beyond the C203? He was picking up the VSS through the C203, and had wires connected to the loose ends of the ECM? I'm going to email him, point him to this thread, and hopefully he can clarify, but can folks also help me out by verifying my wiring?

This is not at all my forte, and any help would be greatly appreciated!

The yellow and purple of the VSS run to the 7730's inputs and no where else.

4000K PPM ECM output runs to the green buffer input

Your pinks are good. The wire size is no problem.

Yellow output of the buffer to C203 G

Nothing connected to C203 R

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So let me ask. What transmission are you running? If it is a Fiero MT or Fiero AT with the Fiero VSS you do not need the speedo buffer, nor do you need to run the VSS signal through the ECM. Instead you can run it to both the inputs of the ECM and have it T spliced so it also runs to C203. This is how Darth is explaining it.

If you have a transmission that has a 24000 PPM VSS then you do need to run it through the ECM, and you also need to have the ECM programmed for the correct divisor (6x) to the 4000 PPM output.

You can run thestock Fiero VSS output to the 7730's VSS input, and use the 4000 PPM ECM output (along with the speedo bufer) and program the ECM for the correct divisor (1x) to run the speedo but there is no gain by doing so.

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The VSS signal needs to be connected to the ECM for the ECM to operate the engine correctly.
The VSS signal needs to either be T spliced (stock Fiero VSS) to the VSS, or fed off of the 4000 PPM ECM output to work correctly.

[This message has been edited by phonedawgz (edited 05-24-2014).]

I'm running a stock 4 speed. I bought the buffer from you because the PO told me I needed a buffer. Then I emailed you:

"Do you make speedo buffers to run a stock Fiero speedo on a 7730 ECM?"

And you replied "Yes." Not looking to point the blame, and its not a big deal. Just letting you know how I got here.

Now I'm really confused.

PO had the VSS running straight to C203, not connected to the ECM, as far as I can tell. BB9, BB10 and BB11 on the 7730 were open. This isn't right, right?

I should omit the buffer, connect BB9 and BB10 to the VSS, and T BB10 into C203 G, yes?

BB11 should just be open, since I don't have cruise, right?

C203 R is also open?

[This message has been edited by onesexyfiero (edited 05-24-2014).]

Well it will run a stock Fiero speedo connected to a 7730. And if you had a MT with a 24,000 PPM VSS you would need it. But since you don't, you don't.

Send it back and I will refund the price.

You won't need to use the green or green/white wire on the 4000 PPM output.

So you should have a yellow and purple wire that runs to the VSS. You should have a yellow and a purple wire that runs to the ECM. And you should have a yellow and purple wire that ran to the pins on C203.

Splice all the yellows together. Then in a separate splice splice all the purples together. That's it.

It is pretty much as you have stated but in C203 R is one of the three purple wires that get spliced together.

[This message has been edited by phonedawgz (edited 05-24-2014).]

Okay, got it now.

I already installed the buffer, so I can't really return it. Not really your fault either. But thank you for offering. It says a lot about you as a businessman.

Long story short it turns out the PO didn't have a functioning speedometer.

You should return it.